1. Field of the Invention
The present invention relates to a developing apparatus and a developing cartridge used with an image forming apparatus such as a copying machine, a printer and the like and particularly used with a color image forming apparatus.
2. Related Background Art
In full-color image forming apparatuses, a developing unit including a yellow developing device, a magenta developing device, a cyan developing device and a black developing device is rotated so that a selected developing device faces an image bearing member.
When such a developing unit is rotated, since it is possible that developer may leak from the unit or that the developer is scattered, it is desirable to prevent postures or attitudes of the developing devices from changing.
Further, at a connection portion between each developing device and its developer replenishing portion, since the separation and connection are effected in order to switch the developing devices for developing a latent image formed on the image bearing member, the developer was particularly apt to leak. Further, in order to exchange a developing device a service life of which has expired, such a developing device must be exchanged by a new one by an expert and the maintenance must also be performed by the expert. To avoid this, it is considered that each of the developing devices is made as a cartridge.
However, when the postures of the developing devices are maintained in a steady condition, since the developing devices are rotated with respect to the developing unit, it is necessary to provide peripheral gaps between the developing devices and the developing unit. In this case, it is difficult to mount the developing cartridges on the developing unit with the peripheral gaps.